J Stötzel et al 2009 J. Phys.: Conf. Ser. 190 012153 doi:10.1088/1742-6596/190/1/012153
J Stötzel1,5, D Lützenkirchen-Hecht1, R Frahm1, B Kimmerle2, A Baiker2, M Nachtegaal3, M J Beier4 and J-D Grunwaldt4,5
Show affiliationsIn the present study the structure of copper catalysts on alumina support were investigated in situ and time resolved during reduction and re-oxidation at different temperatures with the quick-scanning EXAFS (QEXAFS) technique. Different impregnation times (2 min and 90 min) were chosen for the preparation which resulted in different copper species that show a strong variation in the reduction/re-oxidation behaviour. These dynamic changes as well as possible intermediate phases during the gas atmospheres changes were followed with up to 20 EXAFS spectra per second at the copper K-edge covering an energy range of 450 eV. The high time resolution provided new insights into the dynamics of the catalysts e.g. revealing Cu(I) as intermediate state during re-oxidation. Latest advances in the data acquisition hardware are leading to an improved data quality of spectra collected at the SuperXAS beamline. Thus, not only accurate analysis of the catalysts via XANES but also by EXAFS was possible. This is also due to the recent upgrade to monitor the Bragg angle directly with an encoder during the experiments.
78.70.Dm X-ray absorption spectra
64.70.K- Solid–solid transitions
82.30.-b Specific chemical reactions; reaction mechanisms
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
Condensed matter: electrical, magnetic and optical
Surfaces, interfaces and thin films
Issue 1 (2009)
J Stötzel et al 2009 J. Phys.: Conf. Ser. 190 012153
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